Method of removing the enamel from useless enameled utensils.



, on rubbish heaps.

- unserviceable in a boiler which is filled UNITED STATES PATENT oEEioE.

GUSTAV SPITZ, OF BE'U'NN, AUSTRIA-HUNGARY, ASSIGNOR-T0 GOLDSCHMIDT DETIN- NING COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

METHOD OF REMOVING THE ENAMEL FROM USELESS ENAMELED UTENSILS.

1,055,678. No Drawing.

To all whom it may concern i Be it known that I,'GUsTAv Srrrz, manager, a citizen of Austria, residing at Briinn, Province of Moravia, Austria.- Hungary, have invented a new and useful Method of Removing the Enamel from Useless Enameled Utensils; and I do hereby declare the following to be a full, clear, and exact description of the same.

. Enameled utensils which have been damaged during the enameling process are inferior to utensils which are enameled well and uniformly both with regard to their usefulness and also as to their selling price. Enameled utensils which have become unserviceable during use have many inconveniences attaching to them, particularly for large towns, since they can only be destroyed with great difficulty and expense, and therefore large quantities of such utensils which'cannot be done away with are seen Now an important object of the present invention is to provide a method of removing enamel from enameled scrap by means of which on the one hand the metal, and on the other hand the enamel-constituents can be obtained from enameled utensils which have become injured during the enameling process or in use, the sheet iron utensilsfas for example pots, cans, basins and the like, before being covered with enamel being here understood by the word metal. The vessels may then be enameled again fresh, or the same may be used as metal or sheet iron, whereas I use the enamel-constituents which are obtained for making fresh enamel.

I obtain the metal and the enamel-constituents from the useless enameled utensils by placing the utensils which have become Specification of Letters latent.

with aqueous solutions of an alkaline nature. As alkaline solutions I preferably employ caustic soda of about 15 Baum without limiting myself to this agent. The boiler is then closed air-tight and a fire is kept under the same until the solution is heated to above 100 C. and is ata pressure of 7 to 15 atmospheres. According to the size of the boiler in each case or to the quantity of utensils and of the solution in l Patented M r. 11, 1913.

Application filed June 30, 1908. Serial No. 441,980%.

the boiler, the solution is kept for about six to eight hours at the above-mentioned temperature and under the stated pressure, which is done by regulating the fire under the boiler. By this procedure the enamel attaching to the utensils is dissolved in the solution and becomes detached from the utensils, and this separation can be promoted by the utensils being moved. After the boiler has cooled and the lid of the boiler has been opened, the utensils are removed and simply Washed with lukewarm water, and after drying they can either be enameled afresh or sold as'sheet iron.

The enamel-constituents may be obtained from the aqueous solution according to an optional known method, the mentioned aqueoussolutions being simultaneously revivified, in some other manner.

If it is preferred not to obtain the enamelconstituents which have passed into the solution and not to revivify the lye, as is quite'possible owing to the cheapness of its manufacture, it is then most rational to employ this lye instead of soda for neutralizing the acid. The percentage of alkali in the lye has a neutralizing action on the acid which still adheres to the sheet metal, whereas the presence of silicate and borate of soda in the solution affords a much better protection against the utensils subsequently rusting than soda or lime which were employed heretofore. Further, this coating of silicate and acid borate of soda causes the enamel to adhere to metal much better, bothbefore and after it is melted on, and diminishes the formation of bubbles. I have also found that, half the money value of the soda which is generally employed is saved. This lye can also be employed as fireproof paint on wood, and for purifying hard water which is fed into boilers. The silicic acid which can be obtained from this lye, for example, by precipitation by means of "furnace gases, is exceedingly fine and light and can be employed for chemical purposes or as fireproof insulating material.

The enamel which has fallen off from the sheet metal is mixed with about. 20% borax and added to the primary enamel. Accordingly all the constituents of the enameled utensils are rationally employed again in making new ones. v

lVhat I claim as my invention and desire to secure by Letters Patent is:

1. Method of removing the enamel from useless enameled utensils, consisting in treating the enameled utensils with an aqueous solution of an alkaline nature heated to above one hundred. degrees centigrade, and at a pressure of from seven to fifteen atmospheres, whereby the enamel is detached from the utensils.

2. Method of removing the enamel from useless enameled utensils, consisting in treating the enameled utensils with an aqueous solution of caustic soda of 15 Baum, or over, heated to above one'hundred degrees centigrade, and at a pressure of seven to fifteen atmospheres, whereby the enamel is detached from the utensils. 3. Method of removing the enamel from useless enameled utensils, consisting in treat ing the enameled utensils with an aqueous solution of an alkaline nature in a boiler closed air-tight, and heating the utensils in noeaere said solution to a temperature exceeding one hundred degrees centigrade' andat a pressure exceeding seven atmospheres, whereby the enamel is detached from the utensils.

4. A method of removing the enamel from enameled scrap, consisting in treating the enameled scrap with a hot aqueous solution of an alkaline nature at a pressure greatly exceeding atmospheric, whereby the enamel is removed from the scrap.

5. A method of removing the-enamel from enameled scrap, consisting in treating the enameled scrap with a hot aqueous solution of an alkaline nature at a pressure greatly exceeding atmospheric, whereby the enamel is removed from said scrap, and simultaneously maintaining a relative movement between the scrap and said alkaline solution.

In testimony whereof, I have signed my name to this specification in the presence of two subscribing witnesses.

Mo'nrrz SoHMoLKAY, LnoPoLo DRDACKY. 

